The grinding tip of the sea urchin tooth exhibits exquisite control over calcite crystal orientation and Mg distribution

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung

Beitragende

  • Yurong Ma - , Weizmann Institute of Science, Peking University (Autor:in)
  • Barbara Aichmayer - , Max Planck Institute of Colloids and Interfaces (Autor:in)
  • Oskar Paris - , Max Planck Institute of Colloids and Interfaces (Autor:in)
  • Peter Fratzl - , Max Planck Institute of Colloids and Interfaces (Autor:in)
  • Anders Meibom - , Muséum national d'histoire naturelle (Autor:in)
  • Rebecca A. Metzler - , University of Wisconsin-Madison (Autor:in)
  • Yael Politi - , Weizmann Institute of Science (Autor:in)
  • Lia Addadi - , Weizmann Institute of Science (Autor:in)
  • P. U.P.A. Gilbert - , University of Wisconsin-Madison (Autor:in)
  • Steve Weiner - , Weizmann Institute of Science (Autor:in)

Abstract

The sea urchin tooth is a remarkable grinding tool. Even though the tooth is composed almost entirely of calcite, it is used to grind holes into a rocky substrate itself often composed of calcite. Here, we use 3 complementary high-resolution tools to probe aspects of the structure of the grinding tip: X-ray photoelectron emission spec-tromicroscopy (X-PEEM), X-ray microdiffraction, and NanoSIMS. We confirm that the needles and plates are aligned and show here that even the high Mg polycrystalline matrix constituents are aligned with the other 2 structural elements when imaged at 20-nm resolution. Furthermore, we show that the entire tooth is composed of 2 cooriented polycrystalline blocks that differ in their orientations by only a few degrees. A unique feature of the grinding tip is that the structural elements from each coaligned block interdigitate. This interdigitation may influence the fracture process by creating a corrugated grinding surface. We also show that the overall Mg content of the tooth structural elements increases toward the grinding tip. This probably contributes to the increasing hardness of the tooth from the periphery to the tip. Clearly the formation of the tooth, and the tooth tip in particular, is amazingly well controlled. The improved understanding of these structural features could lead to the design of better mechanical grinding and cutting tools.

Details

OriginalspracheEnglisch
Seiten (von - bis)6048-6053
Seitenumfang6
FachzeitschriftProceedings of the National Academy of Sciences of the United States of America : PNAS
Jahrgang106
Ausgabenummer15
PublikationsstatusVeröffentlicht - 14 Apr. 2009
Peer-Review-StatusJa
Extern publiziertJa

Externe IDs

PubMed 19332795
ORCID /0000-0002-2872-8277/work/142239186

Schlagworte

ASJC Scopus Sachgebiete

Schlagwörter

  • Echinoderms, Grinding tool, Self-sharpening, Spectromicroscopy, X-ray microdiffraction